We make the following changes for outbound scanning.

Edit /etc/exim.conf

Look for two instances of:

driver = dnslookup

under dk_lookuphost: and lookuphost:

Comment both instances and add two instances of

driver = manualroute
route_list = * barracuda.outgoing.hostname

so it’ll look something like this:

dk_lookuphost:
#driver = dnslookup
driver = manualroute
route_list = * barracuda.outgoing.hostname

lookuphost:
#driver = dnslookup
driver = manualroute
route_list = * barracuda.outgoing.hostname

then go to Barracuda management panel and go to Basic -> Authorized Senders and enter main ip address of that cpanel server

and restart cpanel exim and check the exim_mainlog

grep barracuda.outgoing.hostname /var/log/exim_mainlog

http://forums.cpanel.net/f43/smtp-relay-barracuda-140997.html

http://help.comodo.com/topic-157-1-288-4545-.html

http://atmail.com/kb/2009/using-smtp-auth-with-the-exim-smarthost/